[ARM platform]Remote snapshotter test failed on pulling image due to microVM time out of sync

[fangn2]

[ARM platform]Remote snapshotter test failed on pulling image due to microVM time out of sync

[BinSquare]

Guest kernels needs to be compiled with KVM_PTP support as a mechanism for clock sync.

CONFIG_PTP_1588_CLOCK=y
CONFIG_PTP_1588_CLOCK_KVM=y

We can see that all the arm microvm kernel configs are missing CONFIG_PTP_1588_CLOCK_KVM=y incomparison to all the x86 configs. This discrepancy is due to 4.14 arm64 missing the feature which has been upstreamed since 5.3, good discussion here as experienced by kata-containers: kata-containers/packaging#693

We can see that the CI build logs indicate that it failed & was using the 4.14 as well.

default-vmlinux.bin: OK
--
  | chmod 0400 default-vmlinux.bin
  | _submodules/firecracker/tools/devtool -y build_kernel --config tools/kernel-configs/microvm-kernel-aarch64-4.14.config

The solution for this issue needs 2 parts:

1. guest kernel configs need the missing property
2. whatever kernel we choose needs to have ptp_kvm commit: https://github.com/torvalds/linux/blob/16a8829130ca22666ac6236178a6233208d425c3/Documentation/virt/kvm/arm/ptp_kvm.rst#L4

[fangn2]

@BinSquare Thanks for taking a look at the issue.
The two parts solution makes sense to me. I did try compiling the kernel with

CONFIG_PTP_1588_CLOCK=y
CONFIG_PTP_1588_CLOCK_KVM=y

But since we don't have the ptp_kvm patch, the change did not make any difference.